The Port Authority official who directed the shutdown of lanes to the George Washington Bridge said that he informed Gov. Chris Christie of New Jersey about it at a Sept. 11 memorial ceremony while the lanes were closed, according to an internal review that lawyers for the governor released on Thursday.

The official, David Wildstein, who was a longtime political ally of the governor, told Mr. Christie’s press secretary, Michael Drewniak, of the conversation at a dinner in December, on the eve of his resignation from the Port Authority of New York and New Jersey, according to the inquiry.

But the report said that Mr. Christie did not recall Mr. Wildstein’s raising the topic during their interaction and, in a sweeping claim of vindication, found no evidence that he — or any current members of his staff — was involved in or aware of the scheme before it snarled traffic for thousands of commuters in Fort Lee, N.J., from Sept. 9 to the morning of Sept. 12.

The inquiry instead blamed, almost entirely, Mr. Wildstein and the governor’s deputy chief of staff, Bridget Anne Kelly, for the scandal, describing Ms. Kelly as scrambling to cover up her role.

Mr. Christie has said previously that he did not know of the lane closings before or while they were occurring, making the account of the purported Sept. 11 exchange between Mr. Wildstein and Mr. Christie perhaps the most provocative revelation in the report, commissioned by the governor at a cost to taxpayers of at least $1 million. Throughout its 360 pages, the document wove together panicked private emails, derisive text messages and descriptions of dramatic confrontations between the Republican governor and his staff as the controversy unfolded. Two parallel investigations, by the New Jersey Legislature and federal prosecutors, are not yet complete.

At a heated televised news conference, the former federal prosecutor who led the internal inquiry, Randy M. Mastro, frequently sounded like a defense lawyer making his case to a jury. He referred to Ms. Kelly as a liar, cast doubt on the credibility of the mayor of Hoboken, who accused the Christie administration of political intimidation, and slipped into lawyerly exhortations to the “ladies and gentlemen” sitting before him.

Mr. Mastro, and his report, went so far as to describe a romantic relationship between Ms. Kelly and a top adviser to Mr. Christie who has been caught up in the imbroglio, seemingly insinuating — without providing specific evidence — that its breakup may have colored her judgment.

The report seemed to anticipate a looming showdown between Mr. Christie and the person who may become the most menacing witness against him: Mr. Wildstein, who, Mr. Mastro said, harbored “bizarre personal and political animus.”

“It will apparently be Wildstein’s contention — as he alleged in early December 2013 to Drewniak — that he mentioned the traffic issue to the governor on that occasion,” the report said, referring to the memorial ceremony, which was held at ground zero. Then it suggested why Mr. Wildstein’s claim should not be given much weight:

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Randy M. Mastro, the lawyer hired by Gov. Chris Christie to lead an internal investigation into the closing of George Washington Bridge access lanes in Fort Lee, N.J., defended the findings.CreditCreditOzier Muhammad/The New York Times

“Whatever brief exchange they had occurred in a public setting where they were surrounded by many, including other Port Authority officials, the governor’s wife, and a steady stream of spectators requesting photographs and handshakes with the governor. Not surprisingly, the governor has no recollection of such an exchange.”

A lawyer for Mr. Wildstein previously said in a letter that “evidence exists” that Mr. Christie knew of the lane closings as they occurred. It was unclear if he was referring to the Sept. 11 encounter; Mr. Mastro clearly thought that he was.

The report did not say whether Mr. Wildstein’s account of the Sept. 11 encounter included telling Mr. Christie why he had orchestrated the closings. Mr. Drewniak told investigators that at their dinner, Mr. Wildstein had called the closings part of a legitimate traffic study.

Mr. Wildstein, Ms. Kelly and Bill Stepien, the former Christie campaign official to whom Ms. Kelly, it was suggested, was romantically linked, all refused to be interviewed for the internal report, raising questions about its thoroughness.

Mayor Dawn Zimmer of Hoboken, a Democrat, also declined to be interviewed; she had accused the Christie administration of threatening to withhold recovery money for Hurricane Sandy if she refused to back a real estate project. The review, conducted by the corporate law firm Gibson Dunn & Crutcher, found her claims groundless.

The report did, however, outline extensive access to Mr. Christie; his lieutenant governor, Kim Guadagno; and the members of their staffs, many of whom turned over their work and private email accounts, cellphones and telephone records.

But for all its tantalizing details, gleaned from a review of 250,000 pages of documents and interviews with more than 70 individuals, the report failed to resolve a central question: What motivated the ham-handed lane closings?

Gibson Dunn lawyers wrote of an “ulterior motive” but could not identify it.

Mr. Wildstein, the report said, had seethed about Fort Lee’s access lanes to the George Washington Bridge for years, calling them an unnecessary and unfair perquisite for a small town.

Still, the report strongly suggested that election-year politics factored heavily into the plot. Newly uncovered testimony and documents show that the night before Ms. Kelly wrote the now infamous email, “time for some traffic problems in Fort Lee,” on Aug. 13, she called a member of the governor’s campaign and asked whether the Democratic mayor of Fort Lee, Mark Sokolich, intended to endorse Mr. Christie for re-election, the report said.

Mr. Sokolich, she was told, would not. It was the first time a specific catalyst for the traffic-problems email was suggested.

Around the same time, Ms. Kelly expressed outrage after learning that a member of her staff had met with the Fort Lee mayor, suggesting that it was a violation of an attempt to freeze out Mr. Sokolich. She described herself as “really upset” and “on fire” over the meeting. A lawyer for Ms. Kelly did not respond to requests for comment.

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David Wildstein said he had told Mr. Christie about the closings.CreditÁngel Franco/The New York Times

The Gibson Dunn lawyers described Mr. Christie as blindsided by a plan that Ms. Kelly and Mr. Wildstein had hatched and determined to learn the truth about his staff’s role.

In one meeting with his senior staff, held after the executive director of the Port Authority had condemned the lane closings as likely illegal, Mr. Christie raised his voice, paced the room and demanded his aides admit to any role in the case, the report recounted. “This is a mess, and now I have to clean it up,” Mr. Christie told them, according to the report.

As the mess expanded, so did attempts by Ms. Kelly to mask her involvement, the report said. In mid-December, hours after the governor’s chief of staff asked her whether she knew anything about the lane closings, she directed an assistant to delete a potentially incriminating email. In the message, Ms. Kelly had expressed pleasure at learning that the lane closings angered Fort Lee’s mayor. “Get rid of that,” she said, according to the report. (The aide did, but saved a copy.)

Mr. Christie later fired Ms. Kelly and cut ties to Mr. Stepien. A longtime friend and counsel, Mr. Stepien confided to another Christie adviser that he was “upset to be thrown under the bus,” the report said.

Despite Ms. Kelly’s senior status, the internal inquiry concluded that her behavior was “aberrational” and dismissed claims from Democrats that the governor fostered or condoned a culture of partisan payback. It called such claims “unsubstantiated.”

“We found that this was the action of the few,” Mr. Mastro said at the news conference, in Gibson Dunn’s offices in Midtown Manhattan. “This is not reflective of the whole.”

Nevertheless, Mr. Mastro and his legal team recommended a series of immediate changes to the structure of the governor’s office: the creation of an ombudsman to begin restoring public trust, the appointment of an ethics officer to train the governor’s staff and the elimination of the intergovernmental affairs office that Ms. Kelly oversaw.

In finding no fault with Mr. Christie in the Hoboken case, the report took a swipe at Ms. Zimmer, the mayor, saying that documents, witnesses and the mayor herself had contradicted her claims. “Our investigation found that Mayor Zimmer’s allegations are, in material respects, demonstrably false,” the report said.

Ms. Zimmer fired back later on Thursday, saying in a statement, “Randy Mastro could have written his report the day he was hired and saved the taxpayers the million dollars in fees he billed in generating this one-sided whitewash.”

Local and national Democrats accused Mr. Christie of rushing out an incomplete internal report to revive his political fortunes and seized on his plans to sit down for a network television interview on Thursday night, then head to Las Vegas this weekend for a Republican conference.

“The idea that Bridget Kelly and David Wildstein by themselves concocted the lane closure is frankly hard to believe,” said State Assemblyman John S. Wisniewski, co-chairman of the legislative committee investigating the case. “Lawyers hired and paid for by the Christie administration will not be the final word on this matter.”

Correction:March 27, 2014

An earlier version of this article misstated some circumstances of an internal investigation into lane closings at the George Washington Bridge. It is Bridget Anne Kelly who is fighting requests from state investigators to turn over personal materials related to the scandal, not Ms. Kelly and David Wildstein.

Reporting was contributed by David W. Chen, William K. Rashbaum, Marc Santora and Kate Zernike.

A version of this article appears in print on , on Page A1 of the New York edition with the headline: Report Details Ex-Ally’s Claim About Christie. Order Reprints | Today’s Paper | Subscribe